The present invention relates to an apparatus for manufacturing a semiconductor device, and more particularly, to a tube apparatus used to grow a layer or diffuse a dopant in manufacturing a semiconductor device.
In manufacturing a semiconductor device, a tube made of quartz is employed in order to grow various structural layers or diffuse a dopant. A quartz tube is generally constituted by a process quartz tube (hereinafter referred to as a process tube) having a silicon wafer for processing, and a dummy tube for venting the gas remaining after the processing.
A process tube is utilized in reacting the reactant gases entering via a gas inlet hole on the silicon wafer to grow a desired layer, or in diffusing doped impurities. The dummy tube is mounted on the process tube and has an outlet hole for venting non-reacted gas remaining in the process tube after reaction, or by-products produced by the reaction. Nitrogen gas is introduced into the dummy tube via a nitrogen curtain tube so that constant pressure in the process tube is maintained, and so that contaminants are prevented from being introduced into the process tube from the outside.
FIG. 1 is a sectional view of a conventional tube apparatus during diffusion process, and FIG. 2 is a cross-sectional view of the tube apparatus of FIG. 1 taken along line A--A'.
In FIGS. 1 and 2, reference number 1 denotes the process tube, 2 denotes a dummy tube, 3 denotes a gas outlet hole, 4 denotes a connecting portion of the process tube 1 and the dummy tube 2, 5 denotes a nitrogen curtain tube, 6 denotes a reactant gas inlet hole, 7 denotes a residue remaining in the dummy tube 2, and 8 denotes a reactant gas.
Firstly, a semiconductor wafer (not shown) is mounted on the process tube 1, and reactant gas 8 is introduced via gas inlet hole 6. At this time, nitrogen gas is introduced into the dummy tube 2 via nitrogen curtain tube 5 and forms a nitrogen curtain in the process tube 1. Reactant gas 8 introduced via gas inlet hole 6 grows a desired layer on the wafer or diffuses doped impurities. The nitrogen gas introduced via nitrogen curtain tube 5 maintains constant pressure in the process tube 1 and prevents the reactant gas 8 from coming into contact with the outside, so that contaminants are prevented from being introduced into the process tube 1.
After the process, non-reacted gas and reaction by-products are vented to the outside via the gas outlet hole 3 of the dummy tube 2.
In the conventional tube apparatus as above, the process tube 1 and the dummy tube 2 are connected to each other and have different temperature variations. For example, the temperature of dummy tube 2 may be lower than that of process tube 1. Accordingly, the high temperature reactant gas and the reaction by-products from the process tube 1 condense to form residue 7 on the inner wall of the dummy tube 2. This residue 7 becomes a contaminant source when the wafer is loaded or unloaded into the process tube 1. Also, since the process tube 1 and the dummy tube 2 are connected to each other, a fine chink or seam exists therebetween. Therefore, not only is heat lost through this chink, but reactant gas also leaks out of this chink to react with vapor in the ambient air so that a strong acidic material forms and solidifies. The process tube 1 and the dummy tube 2 must be firmly coupled, so that they cannot be separated. Therefore, re-using them is difficult. Additionally, since the connection between the process tube 1 and the dummy tube 2 is very important, great care must be taken in process maintenance, which is very time-consuming.
The present inventors have taken the aforementioned problem into consideration and thus accomplished the present invention.